1. Preparing the Ingredients:
Grate the zucchini and carrots. For the zucchini, lightly pat it with a paper towel to remove some excess moisture, but don’t squeeze out too much liquid, as it contributes to the cake’s moistness. Set the grated vegetables aside.

2. Mixing the Wet Ingredients:
In a large bowl, beat together the canola oil and granulated sugar until well combined and slightly fluffy. Add the eggs one at a time, beating well after each addition.

3. Incorporating the Dry Ingredients:
In a separate bowl, sift together the flour, cinnamon, salt, baking soda, and baking powder. Gradually fold the dry ingredients into the wet mixture, being careful not to overmix.

4. Adding Zucchini and Carrots:
Gently fold in the grated zucchini and carrots until evenly distributed throughout the batter.

5. Baking the Cake:
Preheat your oven to 350°F (175°C). Grease a 10×15-inch sheet pan or line it with parchment paper. Pour the batter into the prepared pan, spreading it evenly. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.

6. Cooling the Cake:
Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely before frosting.

7. Making the Cream Cheese Frosting:
In a medium bowl, beat the softened cream cheese and margarine together until smooth. Gradually add the powdered sugar, one cup at a time, beating well after each addition. Add the milk and beat until the frosting is smooth and spreadable.

8. Frosting and Serving:
Once the cake is completely cool, spread the cream cheese frosting evenly over the top. Cut the cake into 30 small bars or squares and serve.